Psych Reading for January 28th Pages 122 131 Sensation and Perception How we sense and conceptualize the world Illusion The way you perceive a stimulus doesn t match its physical reality Sensation The detection of physical energy by our sense organs including our eyes ears skin nose and tongue which then relay information o the brain Perception The brain s interpretation of raw sensory inputs Sensation first allows us to pick up the signals in our environments and perception then allows us to assemble these signals into something meaningful Na ve Realism We often assume that our sensory systems are infallible and that our perceptions are perfect representations of the world around us Sensation Our Senses as Detectives o Transduction Going from the outside world to within Transduction The process by which the nervous system converts an external stimulus into electrical signals within neurons Sense Receptor Transduces a specific stimulus Activation is greatest when we first detect a stimulus Sensory Adaptation Response declines in strength after activation o Psychophysics Measuring the barely detectable Psychophysics The study of how we perceive sensory stimuli based on their physical characteristics Absolute Threshold of a stimulus The lowest level of a stimulus we can detect on 50 percent of the trials when no other stimuli of that type are present Just Noticeable Difference JND The smallest change in the intensity of a stimulus that we can detect Weber s Law States that there s a constant proportional relationship between the JND and the original stimulus intensity The stronger the stimulus the bigger the change needed for a change in stimulus intensity to be noticeable o Signal Detection Theory Describes how we detect stimuli under uncertain conditions Signal to Noise Ratio It becomes harder to detect a signal as background noise increases Response Biases Tendencies to make one type of guess over another when we re in doubt about whether a weak signal is present or absent under noisy conditions o Sensory Systems Stick to One Sense Or Do They Specific Nerve Energies States that even though there are many distinct stimulus energies the sensation we experience is determined by the nature of the sense receptor not the stimulus Rubber Hand Illusion Shows how our senses of touch and sight interact to create a false perceptual experience Synesthesia A condition in which people experience cross modal sensations hearing sounds when seeing a color etc Grapheme Color Synesthesia Numbers and colors mixed up Lexical Taste Synesthesia Words have associated tastes Perception When Our Senses Meet Our Brains Parallel Processing The way our brain multitasks o Parallel Processing We can attend to many sense modalities simultaneously o Bottom Up Processing We construct a whole stimulus from its parts o Top Down Processing Starts with our beliefs and expectations which we then impose on the raw stimuli we perceive Perceptual Hypotheses Guessing what s out there o Perceptual Sets When our expectations influence our perceptions o Perceptual Constancy The process by which we perceive stimuli consistently across varied conditions Size Constancy Our ability to perceive objects as the same size no matter how far away they are from us Color Constancy Our ability to perceive color consistently across different levels of lighting The Role of Attention o Selective Attention Allows us to select one channel and turn off all of the others or at least turn down their volume o The major brain regions that control selective attention are the reticular activating system and the forebrain o Filter Theory of Attention View attention as a bottleneck through which information passes o Cocktail Party Effect Our ability to pick out an important message in a conversation that doesn t involve us o Inattentional Blindness We re surprisingly poor at detecting stimuli in plain sight when our attention is focused elsewhere o Charge Blindess A failure to detect obvious changes in one s environment o Binding Problem Piecing together a vision as a whole o Subliminal Information Processing Many of the sensory inputs to which we re exposed unconsciously many of our actions occur with little or no forethought or deliberation o Subliminal Perception The processing of sensory information that occurs below the level of conscious awareness o Subliminal Persuasions Subthreshold influences over our life decisions Pages 135 158 Seeing The Visual System Light The Energy of Life o Hue The color of a light o We are maximally attuned to three primary colors of light red green o Additive Color Mixing The mixing of varying amounts of three colors and blue o Subtractive Color Mixing Mixing of colored pigments The Eye How We Represent the Visual Realm o Pigments The chemicals responsible for eye color o Pupil A circular hole through which light enters the eye o Cornea A curved transparent layer covering the iris and pupil its shape bends incoming light to focus the incoming visual image at the back of the eye o Lens Bends the light but unlike the cornea the lens changes its curvature allowing us to fine tune the visual image o Accomodation The lenses change shape to focus light on the back of the eyes In this way they adapt to different perceived distances of objects o Myopia Nearsightedness Results when images are focused in front of the rear of the eye due to our cornea being to steep or our eyes too long o Hyperopia Farsightedness Results when our cornea is too flat or our eyes too short The Retina Changing Light Into Neural Activity o Retina A thin membrane at the back of the eye o Fovea The central part of the retina and is responsible for acuity o Acuity Sharpness of vision o The retina contains two types of receptor cells through which light passes Rods Enable us to see basic shapes and forms Cones Give us our color vision o Optic Nerve Contains the axons of ganglion cells travels from the retina to the rest of the brain o Blind Spot The place where optic nerve connects to the retina no rods and devoid of sense receptors Visual Perception Even though different parts of the brain process different aspects of visual perception we perceive whole objects and unified scenes not isolated components Many cells in V1 respond to slits of light of a specific orientation Visual information travels from V1 to higher visual areas called V2 along two major routes Visual cortex o One travels to the upper parts of the parietal lobe o Other travels to the